1H-NMR for conformation elucidation

Hello,
I have having some difficulty determining the conformer and assigning H-NMR peaks for a compound with a N,N-diisopropylacetamidine (R-NH-C(CH3)N(2[CH[2(CH3)]])... essentially a diisopropylamine added to CH3CN (ACN). my H-NMR spectrum (at room temp) in CD3CN consists of:
I have assigned all but the singlets

B singlet at 5.8ppm R-NH
B septet at 4.00 CH connected to the N of the diisopropylaminesinglet 2.37
singlet 2.15
TMS at 1.98
doublet at 1.26ppm methyls from the isopropyl
Very B singlet -4.9 μ-BHB

The E conformation is suspected based on theory and steric repulsions, but i cannot justify it from any of the NMR data I have (1H, variable temp 13C, or 11B)

my best guess in regards to those singles is that both E and unfavorable Z conformations exist in solution.